This invention relates to welding titanium alloys to ferrous metal alloys and more particularly to the development of an intermediate weld metal composition compatible to both titanium and a ferrous metal such that the inherently brittle intermetallic phases of TiFe and TiFe.sub.2 normally formed during a fusing or melting of titanium to a ferrous metal will not be formed, or if formed will be present in such minimal amounts as to not preclude the usefulness of the weld. Additionally the invention relates to joining titanium to a ferrous metal by fusion welding techniques and developing the aforementioned intermediate alloy during the fusion welding process itself.
Titanium alloys have proved impossible to weld properly to ferrous or ferrous based materials, that is, to obtain a weldment of sufficient strength/ductility to be useful. Fusion of these two metals at an interface results in formation of brittle iron-titanium intermetallic compounds, namely or chiefly TiFe and TiFe.sub.2. Nevertheless, it is presently possible to obtain useful welds of titanium alloys to iron alloys by the use of non-fusion welding processes such as friction welding, pressure welding, and explosive bonding. One example of this is shown and described in U.S. Pat. No. 3,038,988 to Kessler et al wherein a titanium liner is welded to a steel sheet support structure in a chemical tank by means of inserting therebetween a vanadium or molybdenum sheet and then resistance welding together all three sheets but without causing fusion of the intermediate vanadium or molybdenum sheet.